Not Applicable.
Automotive vehicle wheels are typically supported on two rows of rolling elements (inboard and outboard bearing members) with opposing angular contact to oppose the moments placed on them in cornering. The wheel is typically attached to a flange on a spindle of a hub on which bearing inner races (cones) are located. A suspension component, attached to control arms, springs, and, in the case of front wheel drive, a steering linkage, typically called a knuckle, is a support for the bearing and wheel. The bearing outer races (cups) are mounted to or within the knuckle. A universal joint, commonly a constant velocity joint (CVJ), which is what is illustrated and described herein, transmits torque from a drive shaft to the wheel hub. The bearing is trapped between the wheel hub and the CVJ. When tapered roller bearings are used, the rollers are typically guided by thrust ribs on the cones of the bearings. Each cone at the end of its thrust rib has a back face, and the back face on the inboard cone is abutted with a face on the CVJ. The rib face which guides the rollers is a substantial distance axially from the back face abutting the CVJ to allow thickness for sufficient strength. This rib width causes the distance from the CVJ to the wheel flange to be larger than necessary, causing difficulty in optimizing the steering geometry of the vehicle. The outboard bearing cone raceway is machined on the spindle, and conventionally, the cone raceway has at its outboard end, a thrust rib, integral with the spindle, which meets the raceway at a sharp intersection, actually, an undercut with a very small radius and chamfer. This produces a stress concentration factor that is as high as 4.0, or higher, in the area between the cone raceway and the flange to which the vehicle wheel is attached.
The use of ribbed cups in tapered roller bearings in vehicle wheel supports is old. Patents to applicant""s assignee and its predecessors directed to the use of such cups extend for over a century, see U.S. Pat. Nos. 606,635 (1898), 2,034,545, 3,397,020, and 5,735,612, for example. However, none has addressed the particular problems to which the present invention is directed, nor suggested the solution that the present invention presents.
One of the objects of this invention is to provide a hub construction that reduces the stress concentration factor.
Another of the objects is to shorten the distance between the universal joint, in the illustrative embodiment a CVJ, and the hub, and to permit a reduction in weight of the hub assembly.
Other objects will occur to those skilled in the art in the light of the following description and accompanying drawings.
In accordance with this invention, generally stated, a wheel bearing assembly is provided which includes a support structure, in the embodiment shown, a knuckle, a universal joint, outboard and inboard bearing members, each having a roller bearing cup fixedly attached to the knuckle, each cup having a tapered roller bearing race, a wheel hub including a spindle having a wheel flange suitable for attaching a wheel, and two cones each having a race, the outboard cone race being machined into the hub. Two sets of rollers are interposed between respective cone and cup races, contacting their races at an angle to the wheel hub axis and opposing each other. The outboard cone race has no thrust rib, and meets the spindle between the race and the wheel flange at a large radius, or none at all, in effect an infinite radius. The thrust rib for the outer bearing member is at the outboard end of the cup raceway. By eliminating the cone thrust rib and its sharp radius, the stress concentration factor at the end of the cone race is greatly reduced or eliminated. Because of that, the spindle section at the outboard raceway can be reduced. If the inboard cone is also made without a thrust rib, and the thrust rib is formed at the inboard end of the cup raceway, the universal joint can be moved closer to the wheel flange by the distance formerly occupied by the thrust rib on the cone, which helps reduce the scrub radius. Alternatively, the thrust rib on the inboard cone can be supplied by a lip on a surface of a universal joint, as of the shell of the CV joint, as described in the application of Hacker, DN8149, to which reference is made above. In either case, the inboard cone has no thrust rib integral with it.